Stop the loader task and listener when a loader ends

Every loader started a timer and registered itself as listener, but neither
was stopped, so each loader kept running every tick until the server
restarted. Both are now stopped when the loader is stopped or replaced by a
new one.

BauSystem/BauSystem_Main/src/de/steamwar/bausystem/features/loader/Loader.java

@@ -36,9 +36,11 @@ import org.bukkit.Bukkit;
 import org.bukkit.Material;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
+import org.bukkit.event.HandlerList;
 import org.bukkit.event.Listener;
 import org.bukkit.event.inventory.ClickType;
 import org.bukkit.event.player.PlayerQuitEvent;
+import org.bukkit.scheduler.BukkitTask;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -63,13 +65,14 @@ public class Loader implements Listener, SWPlayer.Component {
     private List<LoaderElement> elements = new ArrayList<>();
     private int currentElement = 0;
     private long waitTime = 0;
+    private final BukkitTask task;
 
     public Loader(Player p) {
         this.p = p;
         this.recorder = new LoaderRecorder(p, elements);
         Bukkit.getPluginManager().registerEvents(this, BauSystem.getInstance());
 
-        BauSystem.runTaskTimer(BauSystem.getInstance(), () -> {
+        task = BauSystem.runTaskTimer(BauSystem.getInstance(), () -> {
             if (stage != Stage.RUNNING && stage != Stage.SINGLE) return;
             if (!Permission.BUILD.hasPermission(p)) return;
             if (waitTime > 0) {
@@ -136,13 +139,27 @@ public class Loader implements Listener, SWPlayer.Component {
     }
 
     public void stop() {
+        end();
+        if (getLoader(p) == this) {
+            SWPlayer.of(p).removeComponent(Loader.class);
+        }
+    }
+
+    // Also called when the loader is replaced by a new one
+    @Override
+    public void onUnmount(SWPlayer player) {
+        end();
+    }
+
+    private void end() {
         stage = Stage.END;
         if (recorder != null) {
             recorder.stop();
             recorder = null;
         }
         elements.clear();
-        SWPlayer.of(p).removeComponent(Loader.class);
+        task.cancel();
+        HandlerList.unregisterAll(this);
     }
 
     public boolean setTicksBetweenShots(int delay) {